Sediment samples were extracted for 60 min using a 100-μm PDMS fiber. Fig 6 shows the response for all OCPs after adding of different solvents. The highest response was obtained when 5 mL of water was added to the spiked
sediment while the response of OCPs with the presence of methanol:water(1:1), acetone:water(1:1), methanol and acetone were not observed. The enhanced sensitivity obtained when adding water to sediment could be due to the displacement of analytes from the active sites in the sediments and to the low solubility of the target analyte in water (2).